As many as five national newspapers could fold within two years in a worst-case scenario as the media suffers unprecedented carnage, Guardian News & Media executive Emily Bell has warned.

Bell, the GNM director of digital content, warned that broadcasters, national and regional media were in the middle of a systemic collapse in advertising and not a cyclical downturn.

In presenting what she said was an "in extremis gloomy vision" to the thinktank Polis last night, Bell said that newspapers were closing in the US and that the same could happen in Britain.

"We are on the brink of two years of carnage for western media. In the UK, five nationals could go out of business and we could be left with no UK-owned broadcaster outside of the BBC," she said last night.

"We could face complete market failure in some areas of regional papers and some areas of commercial radio," she added.

Bell pointed out that the New York Times' revenues fell 12% before the current credit crunch took hold and merchant bank Lehman Brothers collapsed.

"This is systematic collapse not just a cyclical downturn. Even the surviving brands will have to go through a period of unprofitability," she said.

Bell said that media organisations would in the future turn to a more "superstar culture" with journalists such as the BBC business editor, Robert Peston, rising to the fore.

They would continue to publish and broadcast packaged stories, but would gain greater authority through their own blogs and their own unfiltered journalistic voice, she added.

GNM publishes the Guardian, Observer and the guardian.co.uk website network, including MediaGuardian.co.uk.

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